1. Field of the Invention
The present invention relates to proton exchange membranes, and in particular relates to the composition and the formula for improving degree of swelling and dimensional stability of the proton exchange membranes.
2. Description of the Related Art
Film or membrane is important for many industrial fields. Films are modified according to specific properties for application as perm-selective membranes, or so-called proton exchange membranes, for electro analysis, electrolysis, dialysis, or fuel cells. Fuel cells directly transfer chemical energy to electrical energy, wherein an anode and a cathode are separated by a proton exchange membrane. As such, only protons transfer through the membrane.
Sulfonated poly(ether ketone)s, is one type of ion exchange membrane used for operating temperatures less than 70° C. Ion exchange sulfonated poly(ether ketone) membranes have chemical stability, thermal stability, and mechanical strength. However, under operating temperatures higher than 70° C., ion exchange sulfonated poly(ether ketone) membranes dramatically swelled and eventually dissolved. Nevertheless, if problems with dimensional deformation at high temperatures can be solved, then ion exchange sulfonated poly(ether ketone) membranes would be a very suitable proton exchange membrane in fuel cells due to its excellent electrochemical properties.
Accordingly, a novel sulfonated poly(ether ketone) with improved chemical stability and mechanical strength for high temperature fuel cells is called for.